1. Field of the Invention
The present invention relates to a hydraulic system of a vehicle transmission device, and in particular, to improvement on cooling performance of Automatic Transmission Fluid (ATF) oil in a high speed area.
2. Description of Related Art
In the following Patent Document 1, the following structure is expressed for a vehicle transmission device: after discharged oil of a torque converter in a lock-up clutch separation/engagement state is guided, via a first oil path, to a cooler for cooling, the cooled oil is supplied to a lubricating path; after excess oil from a regulator valve is guided, via a second oil path, to the cooler for cooling, the cooled oil is supplied to the lubricating path, and the regulating oil regulates hydraulic pressure discharged from an oil pump. Orifices are disposed in the first oil path and the second oil path respectively, to limit flows guided from respective oil paths to the cooler respectively. In addition, the excess oil from the regulator valve returns to the upstream of the oil pump, and the flow guided from the second oil path to the cooler is limited through the orifice, thus ensuring the flow of the excess oil returning to the upstream of the oil pump.